In larger projects, bulk material of the asphalt type and the like is generally deposited with the use of special, self-driven machines, which are fed with material directly by tipping from the deck of a load-carrying vehicle moving in front of the machine.
In depositing material on a comparatively smaller scale, or where conditions do not permit the use of machines of the type just mentioned, e.g. on garage ramps, footpaths, pavements, slopes etc, the material must be unloaded from the load-carrying vehicle and spread manually, i.e. with shovels handled by workmen. This job is very heavy and wearing (a workman may unload and spread more than 15 tons of material during a working day) and often gives permanent wear injuries, e.g. in the back and shoulders of the workman. There is thus a great need of some aid which could take over the actual work of unloading and spreading heavy bulk material from the workmen.
An asphalt spreader has been proposed (see SE-B-7602592-3) comprising an asphalt container carried on a truck deck, there being swingably connected to the rear outlet end of the container an arm-like discharge conveyor for spreading the material over contiguous ground when the material is discharged. The material is intended to be fed out from the container by gravity to the connecting conveyor end. The conveyor is carried in a special carriage, such as to allow the conveyor to be thrust in under the truck deck when the conveyor is not used. In other words, the entire asphalt spreader is intended to be mounted on a truck and accompany it the whole time, i.e. it is tied to a single truck. This type of asphalt spreader has not been found to function satisfactorily or with the necessary economy, and neither has it come to be actually used to any notable extent.
It has also been proposed (see CH-A-473278) to connect to a truck a smaller spreading apparatus running on its own wheels, which is fed by gravity with material from the truck deck and spreads out received material over contiguous ground by using feed screws and endless conveyors. The apparatus requires an extensive frame structure and releases the material to the ground from a comparatively great height, making the apparatus less flexible and comparatively difficult to operate, as well as impossible to use when difficultly-worked asphalt masses are used. Such materials may not, for example, be fed out with a large drop, since there is then obtained an unacceptable premature compression of the material.